Optimal nutrition is essential for successful cancer treatment as it can decrease symptom burden, improve the overall quality of life, and support survivorship. Cancer diagnosis is often accompanied by a drastic change in diet, including the elimination of animal products. While incorporating more plant based foods provides a number of health benefits, eliminating all animal products during cancer treatment is not recommended.
Clinical Nutrition, the official Journal of the European Society for Clinical Nutrition and Metabolism, recently reviewed findings on the potential impact of protein on muscle anabolism in cancer being associated with better patient outcomes. The opinion paper presents a summarized review of the protein sources, animal vs. plant and which are most beneficial for oncology patients.
What is Muscle Anabolism? Or Anabolic vs. Catabolic?
Anabolism and catabolism are two categories of biochemical reactions that make up metabolism. Anabolism is the organization of simple molecules being built up into larger, complex molecules. This centers around bone growth mineralization and muscle mass build up, which requires energy.
Catabolism is the breakdown of complex molecules into simpler ones, releasing energy. An example of this is when we digest our food. Protein is broken down into amino acids, triglycerides into fatty acids and glycogen into glucose.
Muscle loss is a serious problem in cancer patients. Nausea, loss of appetite and taste alterations are common side effects of cancer therapy which can often result in muscle catabolism.
Animal vs. Plant
Dietary proteins provide essential amino acids required for muscle health. In this review, animal proteins include beef, pork, chicken, fish, eggs, milk, cheese etc. Plant proteins include beans, lentils, soy, nuts etc. The nutritional value of protein comes down to the quality and quantity of amino acids which is measured using the protein digestibility corrected amino acid score or PDCAAS. Plant based proteins have a lower PDCAAS score than animal-based proteins, with the exception of soy protein isolate.
Animal proteins provide more anabolic stimuli compared to plant based protein foods. Plant based proteins resist proteolysis (breakdown of protein into amino acids) in the gastrointestinal tract, making them more difficult to digest, which can be of concern for patients with GI cancers. Leucine, an essential amino acid, is critical for new muscle protein synthesis. Animal proteins contain more leucine than plant-based proteins. This means that you would need to eat more plant-based protein to get adequate leucine. Of the plant based proteins, soyfoods contain the most leucine.
The article mentions an observational and cross sectional study conducted by The British Journal of Nutrition on healthy women both omnivore and vegetarians. The study results showed those who consumed ~68% of their protein from animal sources had significantly higher muscle mass compared with vegetarians consuming ~55% of their protein from animal sources.
Dietitian tip: Nutritional oncology guidelines recommend a minimum intake of 1.0g protein per kilogram of body weight per day, but suggest a target consumption of 1.2-2.0g/kg/d.
There is still abundant research needed to determine the optimal amino acid composition to support overall muscle health in cancer patients. The inclusion of more plant based proteins is supported, however, the journal cautions against making drastic changes to eliminate animal proteins from your diet when you are diagnosed with cancer. Based on these findings, animal protein offers superior anabolic potential compared to plant based proteins. In summary, the combination of animal proteins representing the majority of protein intake (>65%) and plant based protein sources, promote muscle anabolism optimally during active cancer treatment. Dietary changes can be optimized with the help of a registered dietitian nutritionist.
- Berrazaga I, Micard V, Gueugneau M, Walrand S. The Role of the Anabolic Properties of Plant- versus Animal-Based Protein Sources in Supporting Muscle Mass Maintenance: A Critical Review. Nutrients. 2019;11(8):1825. Published 2019 Aug 7. doi:10.3390/nu11081825
- Ford KL, Arends J, Atherton PJ, et al. The importance of protein sources to support muscle anabolism in cancer: An expert group opinion. Clin Nutr. 2022;41(1):192-201. doi:10.1016/j.clnu.2021.11.032
- Marcin, Ashley. “Catabolism vs. Anabolism: Hormones, Body Weight, and Exercises.” Healthline, Healthline Media, 6 Aug. 2019, www.healthline.com/health/catabolism-vs-anabolism.